The invention relates to a roaming interworking gateway (RIG) for interworking of two non-compatible mobile telecommunications systems such as those based on the GSM, IS.41, and PDC standards. Such systems are often alternatively referred to as networks.
Several such gateways are known and are described, for example, in WO 95/27382 (L. M. Ericsson), WO 95/01069 (Vodaphone), EP 379642 (GTE), WO 94/05129 (L. M. Ericsson), and WO 96/24226 (Qualcomm). It appears that these specifications are quite effective at allowing interworking of two non-compatible systems for which they are built. However, the demand for production of gateways for a wide variety of different non-compatible systems such as different systems working within the general IS.41 standard in the U.S.A., the European-based GSM, the Japanese PDC, and various other systems such as those in Asia, is difficult to meet because of the long lead times which are involved in development of the systems. This is because they are specifically programmed for the particular pair of non-compatible systems, and they are often integrated with switches in hardware. A related disadvantage is that they are difficult to modify and upgrade and it is also difficult to extend the interworking capabilities as interworking requirements grow.
It is therefore an object of the invention to provide a RIG which is easily scalable and is easily modified to adapt to changing circumstances. More particularly, it is also an object of the invention to provide a RIG which provides at least some of the following services:
to allow subscribers of one system to roam transparently in another system and to receive and make calls using their home telephone number,
to support billing services for different types of roamers,
to preserve, where possible, supplementary services between the systems where that service can be provided, such as call forwarding, and
to provide additional services to roamers when visiting a system.
According to the invention, there is provided a roaming interworking gateway for interworking of at least two mobile telecommunication systems having non-compatible standards, the gateway comprising:
a modular unit associated with a first mobile system and comprising a pseudo network element of the first system;
a modular unit associated with a second mobile system and comprising a pseudo network element for the second system; and
an interworking translation function linking the modular units and comprising means for performing data and protocol conversion between the units.
Preferably, each modular unit comprises at least two pseudo network elements at different hierarchal mobile system levels.
In one embodiment, each modular unit comprises a pseudo HLR, and a pseudo MSC or VLR or both an MSC and a VLR.
Ideally, each pseudo HLR comprises means for routing signalling set-up signals for a terminating call to a visited system, the MSC or VLR comprising means for receiving such signals from a home system.
In another embodiment, each modular unit comprises an authentication function comprising means for authenticating roamers in the associated mobile system domain.
Preferably, each modular unit comprises a MAP-Interface which comprises means for accessing a database.
In one embodiment, the translation function comprises a translation module interacting with the MAP-User of each MAP-Interface and comprising means for accessing a database.
In a further embodiment, said database access means comprises means for directing storage of subscriber profile data when a subscriber roams in one of the associated mobile systems to provide profile translation in a transparent manner. Ideally, each modular unit resides on a network access processor.
Preferably, the translation function comprises at least two translation modules residing on one or more network access processors.
In another embodiment, the gateway comprises a high speed network linking hardware machines in a distributed manner.
Preferably, the gateway further comprises an operations and maintenance processor connected to the network.
Ideally, the gateway further comprises a billing conversion function.
In one embodiment, the billing conversion function resides on an operations and maintenance processor of the gateway.
The invention will be more clearly understood from the following description of some embodiments thereof, given by way of example only with reference to the accompanying drawings, in which,